TW202225126A - Diamond sintered body, and tool comprising diamond sintered body - Google Patents

Abstract

This diamond sintered body includes diamond particles, wherein the content of the diamond particles is 80 vol% to 99 vol% with respect to the diamond sintered body, the average particle diameter of the diamond particles is 0.1 [mu]m to 50 [mu]m, and the dislocation density of the diamond particles is 1.2*10<SP>16</SP> m<SP>-2</SP> to 5.4*10<SP>19</SP>m<SP>-2</SP>.

Description

Diamond sintered body, and tool with diamond sintered body

The present invention relates to a diamond sintered body and a tool provided with the diamond sintered body.

Since the diamond sintered body not only has excellent hardness, but also has no directionality and cleavage of hardness, it is widely used in tools such as cutting tools, dressers and molds, and excavation drills.

In the previous diamond sintering system, the powder of the diamond as the raw material is combined with sintering aids or binding materials to keep the diamond thermodynamically stable at high pressure and high temperature (generally, the pressure is about 5-8 GPa and the temperature is 1300-2200 ℃. It is obtained by sintering under the conditions of about) . As the sintering aid, iron group element metals such as Fe, Co, and Ni, carbonates such as CaCO ₃ , and the like can be used. As the bonding material, ceramics such as SiC can be used.

For example, Japanese Patent Laid-Open No. 2005-239472 (Patent Document 1) discloses a high-strength, high-wear-resistance diamond sintered body comprising sintered diamond particles having an average particle size of 2 μm or less, and a remainder of A bond phase, and is characterized in that: the content rate of the sintered diamond particles in the diamond sintered body is not less than 80% by volume and not more than 98% by volume; At least one or more elements selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium and molybdenum in an amount of 50% by mass, and the content in the above-mentioned combined phase is not less than 50% by mass and less than 50% by mass 99.5 mass % of cobalt, part or all of the above-mentioned at least one element selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium and molybdenum carbide particles with an average particle size of 0.8 μm or less In this form, the structure of the carbide particles is discontinuous, and the adjacent diamond particles are bonded to each other. In addition, Patent Document 1 discloses a method for producing a high-strength, high-wear-resistance diamond sintered body, which is the above-mentioned method for producing a high-strength, high-wear-resistance diamond sintered body, and is characterized in that a belt-type ultra-high pressure is used. The device is sintered at a pressure of 5.7 GPa or more and 7.5 GPa or less and a temperature of 1400°C or more and 1900°C or less. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2005-239472

The diamond sintering system of the present invention includes diamond particles, and the content of the diamond particles is 80% by volume to 99% by volume relative to the diamond sintered body, and the average particle diameter of the diamond particles is 0.1 μm to 50 μm. , the dislocation density of the diamond particles is 1.2×10 ¹⁶ m ^-2 or more and 5.4×10 ¹⁹ m ^-2 or less.

The tool of the present invention includes the above-mentioned diamond sintered body.

[Problems to be Solved by Invention] When the diamond sintered body of Patent Document 1 is applied to a cutting tool or the like, the cutting edge may be damaged. In addition, in recent years, more efficient (for example, higher feed rate) cutting processing is required, and further improvement in the performance of the diamond sintered body (for example, suppression of crack propagation, etc.) is expected.

The present invention was made in view of the above-mentioned circumstances, and an object thereof is to provide a diamond sintered body having excellent crack propagation resistance, and a tool provided with the diamond sintered body.

[Effect of the present invention] According to the present invention, it is possible to provide a diamond sintered body having excellent crack propagation resistance, and a tool including the diamond sintered body.

[Description of Embodiments of the Present Invention] First, embodiments of the present invention will be described. [1] The diamond sintering system of one aspect of the present invention includes diamond particles, and the content rate of the diamond particles is 80% by volume to 99% by volume relative to the above-mentioned diamond sintered body, and the average particle size of the diamond particles is The dislocation density of the diamond particles is 1.2×10 ¹⁶ m ^-2 or more and 5.4×10 ¹⁹ m ^-2 or less.

The above-mentioned diamond sintered body has excellent crack propagation resistance. Here, the term "crack propagation resistance" refers to the resistance to propagation of cracks generated in the diamond sintered body during cutting when an external force is applied.

[2] The dislocation density of the above-mentioned diamond particles is preferably 1.5×10 ¹⁶ m ^-2 or more and 1.0×10 ¹⁷ m ^-2 or less. By specifying in this way, the crack growth resistance of the diamond sintered body is further improved.

[3] Preferably, the above-mentioned diamond sintered body further includes a bond phase, and The above combination contains: At least one selected from the group consisting of the following elemental metals, alloys, and intermetallic compounds, wherein the elemental metals, alloys, and intermetallic compounds include elements selected from Group 4, Group 5, and Group 6 of the periodic table , at least one metal element from the group consisting of iron, aluminum, silicon, cobalt and nickel; or At least one selected from the group consisting of the following compounds and solid solutions from the above compounds, the above compounds are selected from the group 4 elements, group 5 elements, and group 6 elements of the periodic table, iron, aluminum, silicon , at least one metal element from the group consisting of cobalt and nickel, and at least one non-metal element selected from the group consisting of nitrogen, carbon, boron and oxygen. By specifying in this way, the crack growth resistance of the diamond sintered body is further improved.

[4] The above-mentioned bonding phase preferably contains cobalt. By specifying in this way, the crack growth resistance of the diamond sintered body is further improved.

[5] A tool according to an aspect of the present invention includes the above-mentioned diamond sintered body.

Since the above-mentioned tool has a diamond sintered body excellent in crack propagation resistance, it has excellent fracture resistance and excellent impact resistance when machining various materials. Here, the so-called "breakage resistance" refers to the resistance to the defect that occurs when the tool is processing the material. The so-called "impact resistance" refers to the resistance to momentary force applied from the outside when the material is processed.

[Details of Embodiments of the Present Invention] Hereinafter, the details of the embodiment of the present invention will be described. In addition, this invention is not limited by these illustrations. Here, in this specification, the expression in the form of "A to Z" refers to the upper and lower limits of the range (that is, A or more and Z or less), and when A does not describe a unit but only Z describes a unit, the unit of A is Same unit as Z.

≪Diamond sintered body≫ The diamond sintered system of the present embodiment contains diamond particles, and the content rate of the above-mentioned diamond particles is 80% by volume to 99% by volume relative to the above-mentioned diamond sintered body, and the average particle size of the diamond particles is 0.1 μm or more and 50 μm or less, and the dislocation density of the above-mentioned diamond particles is 1.2×10 ¹⁶ m ^-2 or more and 5.4×10 ¹⁹ m ^-2 or less.

The above-mentioned diamond sintered body contains diamond particles. That is, the diamond sintering system is basically composed of diamonds as particles. In one aspect of this embodiment, diamond particles can also be understood as crystal grains of diamonds. The above-mentioned diamond sintered body preferably further includes a bonding phase (binder) formed by one or both of a sintering aid and a bonding material. The above-mentioned diamond particles and the above-mentioned bonded phase will be described later.

The above-mentioned diamond sintering system includes a polycrystalline body of a plurality of diamond particles. Therefore, the above-mentioned diamond sintered body has no orientation (anisotropy) and cleavage like a single crystal, but has isotropic hardness and crack growth resistance in all orientations.

The diamond sintered body may contain unavoidable impurities within the range in which the effects of the present embodiment are exhibited. As an unavoidable impurity, hydrogen, oxygen, etc. are mentioned, for example.

＜Diamond Particles＞ (content rate of diamond particles) In the present embodiment, the content of the diamond particles is 80% by volume or more and 99% by volume or less, preferably 80% by volume or more and 90% by volume or less, with respect to the above-mentioned diamond sintered body.

The content ratio (volume %) of diamond particles in the diamond sintered body and the content ratio (volume %) of the following binding phase can be confirmed by using a scanning electron microscope (SEM) (manufactured by Nippon Electronics Co., Ltd.). Energy dispersive X-ray analyzer (EDX) (Octane Elect EDS (Energy Dispersive Spectroscopy) system) (hereinafter, also referred to as "SEM-EDX") attached to "JSM-7800F" (trade name) ), microstructure observation, elemental analysis, etc. were performed on the diamond sintered body. The specific measurement method is as follows.

First, cutting is performed at any position of the diamond sintered body, and a sample including the cross-section of the diamond sintered body is produced. For the fabrication of the cross section, a focused ion beam apparatus, a cross section polisher apparatus, and the like can be used. Next, the above-mentioned cross section was observed by SEM, and a backscattered electron image was obtained. In the reflected electron image, the area where diamond particles are present becomes a black area, and the area where a combined phase exists becomes a gray area or a white area. The magnification at the time of observing the above-mentioned cross section by SEM is appropriately adjusted so that the number of diamond particles observed in the measurement field is 100 or more. For example, when the average particle diameter of the diamond particles is 0.5 μm, the magnification of observing the above-mentioned cross section by SEM can be 10,000 times. When the average particle diameter of the diamond particles is 30 μm, the magnification of observing the above-mentioned cross section by SEM can be 200 times.

Next, the above-mentioned reflected electron image is subjected to binarization processing using image analysis software ("Win ROOF ver.7.4.5", "WinROOF2018", etc. of Mitani Corporation). The above-mentioned image analysis software automatically sets an appropriate binarization threshold based on image information (threshold is not arbitrarily set by the measurer). Furthermore, the inventors and the like have confirmed that the measurement result does not change significantly even when the brightness of the image or the like is changed. According to the binarized image, the area ratio of the pixels from the dark field (pixels from the diamond particles) in the area of the measurement field is calculated. By considering the calculated area ratio as volume %, the content ratio (volume %) of diamond particles can be obtained.

By calculating the area ratio of the pixels from the bright field (pixels from the binding phase) in the area of the measurement field of view based on the binarized image, the content rate (volume %) of the binding phase can be obtained.

The inventors of the present invention have confirmed that as long as the content of diamond particles (% by volume) in the diamond sintered body and the content (% by volume) of the following binding phase are measured for the same sample, the measurement can be performed even if the selected portion of the measurement field of view is changed. There is almost no difference in the measurement results after multiple calculations. That is, the present inventors considered that even if the measurement field of view is arbitrarily set, it does not change arbitrarily.

In addition, the fact that the pixels from the dark field are derived from diamond particles can be confirmed by elemental analysis of the diamond sintered body by SEM-EDX.

(Average particle size of diamond particles) The average particle diameter of the diamond particles is 0.1 μm or more and 50 μm or less, preferably 0.2 μm or more and 40 μm or less. When the average particle diameter of the diamond particles is 0.1 μm or more, the diamond particles are densely sintered, and the diamond sintered body has excellent fracture resistance. When the average particle diameter of the diamond particles is 50 μm or less, the diamond sintered body does not have anisotropy, so that it is excellent in cutting stability when used as a cutting edge of a cutting tool.

In this embodiment, the average particle diameter of the diamond particles refers to the value obtained by the following method, that is, in each measurement field of view at 5 places randomly selected, the median diameter d50 of the plurality of diamond particles is respectively measured, and calculated. Take the average value. The specific method is as follows.

First, cutting is performed at any position of the diamond sintered body, and a sample including the cross-section of the diamond sintered body is produced. For the fabrication of the cross section, a focused ion beam apparatus, a cross section polisher apparatus, and the like can be used. Next, the above-mentioned cross section was observed by SEM, and a backscattered electron image was obtained. In the reflected electron image, the area where diamond particles are present becomes a black area, and the area where a combined phase exists becomes a gray area or a white area. The magnification at the time of observing the above-mentioned cross section by SEM is appropriately adjusted so that the number of diamond particles observed in the measurement field is 100 or more. For example, when the average particle diameter of the diamond particles is 0.5 μm, the magnification of observing the above-mentioned cross section by SEM can be 10,000 times. When the average particle diameter of the diamond particles is 30 μm, the magnification of observing the above-mentioned cross section by SEM can be 200 times.

For the five SEM images, image processing software ("Win ROOF ver.7.4.5" and "WinROOF2018" of Mitani Shoji Co., Ltd.) were used in the state where the grain boundaries of the diamond particles observed in the measurement field were separated. ", etc.) to calculate the circle equivalent diameter of each diamond particle. At this time, diamond particles that partially exceed the above-mentioned measurement field of view are not counted.

According to the calculated distribution of the circle-equivalent diameter of each diamond particle, the median diameter d50 in each measurement field of view is calculated, and the average value thereof is calculated. This average value corresponds to the average particle size of the diamond particles.

Furthermore, the present inventors have confirmed that, as long as the average particle diameter of the diamond particles is calculated for the same sample, even if the selected part of the measurement field of view in the diamond sintered body is changed to perform the calculation several times, there is almost no difference in the measurement results. . That is, the present inventors considered that even if the measurement field of view is arbitrarily set, it does not change arbitrarily.

(Dislocation Density of Diamond Particles) The dislocation density of the diamond particles is 1.2×10 ¹⁶ m ^-2 or more and 5.4×10 ¹⁹ m ^-2 or less, preferably 1.5×10 ¹⁶ m ^-2 or more and 1.0×10 ¹⁷ m ^{- 2} or less. Since the dislocation density of the diamond particles is 1.2×10 ¹⁶ m ^-2 or more, there are relatively many immobile dislocations, so that the crack propagation generated in the diamond particles is suppressed, and the crack propagation resistance of the diamond sintered body is improved. become excellent. When the dislocation density of the diamond particles is 5.4×10 ¹⁹ m ⁻² or less, the occurrence of cracks in the diamond particles is suppressed, and the impact resistance of the diamond sintered body becomes excellent.

The relationship between the dislocation density of the diamond particles in the diamond sintered body and the physical properties of the diamond sintered body has not been paid attention to before. Therefore, the present inventors have made efforts to investigate the relationship between the dislocation density of the diamond particles in the diamond sintered body and the crack growth resistance of the diamond sintered body. As a result, it was found for the first time that if the dislocation density of the diamond particles was increased compared with the diamond sintered body that existed before, the sliding motion in the (111) crystal plane in the diamond particles was suppressed, and the crack growth resistance was obtained. promote. Furthermore, according to this investigation, it became clear that the dislocation density of diamond particles in the conventional diamond sintered body (for example, the diamond sintered body described in Patent Document 1) was 1.01×10 ¹⁶ m ⁻² or more and less than 1.18×10 ¹⁶ m ^-2 .

In this specification, the dislocation density of the diamond sintered body is measured in a large-scale radiation facility (eg, Kyushu Synchrotron Light Research Center (Saga Prefecture)). Specifically, it is measured by the following method.

Prepare samples consisting of diamond sintered bodies. The size of the sample is 3 mm × 6 mm for the observation surface, and the thickness is 0.4 mm. Using diamond slurry with an average particle size of 3 μm, the observation surface of the sample was mirror-polished, and then immersed in hydrochloric acid for 72 hours. Thereby, in the observation surface of the sample, the bonded phase was dissolved in the hydrochloric acid, and the diamond particles remained.

For this sample, X-ray diffraction measurement was performed under the following conditions to obtain (111), (220), (311), (331), (422), (440), (531) which are the main orientations of the diamond. ) of the line profiles of diffraction peaks at each plane.

(X-ray diffraction measurement conditions) X-ray source: radioactive light Device condition: Detector NaI (fluorescence cut off by appropriate ROI) Energy: 18 keV (wavelength: 0.6888 Å) Spectrocrystalline: Si(111) Incident slit: width 3 mm × height 0.5 mm Light receiving slit: Double slit (width 3 mm x height 0.5 mm) Mirror: Platinum coated mirror Incidence angle: 2.5 mrad Scanning method: 2θ～θ scanning Measured peaks: 7 diamonds (111), (220), (311), (331), (422), (440), (531). However, when it is difficult to obtain an outline due to texture, orientation, etc., the peak of the surface index is excluded. Measurement conditions: 9 or more measurement points in the full width at half maximum corresponding to each measurement peak. The peak top intensity was set to 2000 counts or more. Since the lower edge of the peak is also used for analysis, the measurement range is set to about 10 times the full width at half maximum.

The shape of the spectral line profile obtained by the above-mentioned X-ray diffraction measurement includes both the true spread caused by physical quantities such as uneven strain of the sample, and the spread caused by the device. In order to determine the non-uniform strain and crystallite size, the components caused by the device were removed from the measured spectral line profile to obtain the true spectral line profile. The true spectral line profile is obtained by fitting the obtained spectral line profile and the spectral line profile generated by the device using a pseudo-Voigt (Pseudo-Voigt) function, and subtracting the spectrum generated by the device line silhouette. LaB ₆ was used as a standard to remove the diffraction line spread caused by the device. Furthermore, in the case of using radiated light with a high degree of parallelism, the ray spread caused by the device can also be regarded as zero.

The dislocation density was calculated by analyzing the obtained real spectral line profiles using the modified Williamson-Hall method and the modified Warren-Averbach method. The modified Williamson-Hall method and the modified Warren-Averbach method are well-known spectral line profile analysis methods for finding the dislocation density.

The formula for modifying the Williamson-Hall method is shown in the following formula (I). [Number 1]

In the above formula (I), ΔK represents the half-value width of the spectral line profile. D represents crystallite size. M represents a configuration parameter. b represents the Burgers vector. ρ represents the dislocation density. K represents the scattering vector. O(K ² C) represents a higher order term of K ² C. C represents the mean value of the contrast factor.

C in the above formula (I) is represented by the following formula (II). C=C _h00 [1-q(h ² k ² +h ² l ² +k ² l ² )/(h ² +k ² +l ² ) ² ] (II)

In the above formula (II), the respective contrast factor C _h00 of screw dislocation and edge dislocation and the coefficient q related to the contrast factor are calculated using the calculation code ANIZC, the sliding system is <110>{111}, the elastic stiffness is C ₁₁ is 1076 GPa, C ₁₂ is 125 GPa, and C ₄₄ is 576 GPa. In the above formula (II), h, k and l correspond to the Miller index (hkl) of the diamond, respectively. The contrast factor C _h00 is 0.183 for screw dislocation and 0.204 for edge dislocation. The coefficient q related to the contrast factor is 1.35 for screw dislocation and 0.30 for edge dislocation. Furthermore, the screw dislocation ratio was fixed at 0.5, and the edge dislocation ratio was fixed at 0.5.

In addition, between the dislocation and the uneven strain, the relation of the following formula (III) is established using the contrast factor C. In the following formula (III), _Re represents the effective radius of dislocation. ε(L) represents uneven strain. <ε(L) ² >=(ρCb ² /4π)ln(R _e /L) (III)

From the relationship of the above formula (III) and the Warren-Averbach formula, it can be expressed as the following formula (IV), and the dislocation density ρ and the crystallite size can be obtained as a modified Warren-Averbach method. In the following formula (IV), A(L) represents a Fourier series. A ^S (L) represents the Fourier series related to the crystallite size. L represents the Fourier length. lnA(L)=lnA ^S (L)－(πL ² ρb ² /2)ln(R _e /L)(K ² C)+O(K ² C) ² (IV)

Details of the modified Williamson-Hall method and the modified Warren-Averbach method are described in "T. Ungar and A. Borbely," The effect of dislocation contrast on x-ray line broadening: A new approach to line profile analysis" Appl. Phys. Lett ., vol. 69, no. 21, p. 3173, 1996.” and “T. Ungar, S. Ott, P. Sanders, A. Borbely, J. Weertman,” Dislocations, grain size and planar faults in nanostructured copper determined by high resolution X-ray diffraction and a new procedure of peak profile analysis"Acta Mater., vol. 46, no. 10, pp. 3693-3699, 1998."

The inventors of the present invention have confirmed that, as long as the dislocation density of diamond particles is measured on the same sample, even if the selected part of the measurement range is changed and the calculation is performed multiple times, there is little difference in the measurement results. That is, the present inventors considered that even if the measurement field of view is arbitrarily set, it does not change arbitrarily.

＜Combined Phase＞ In this embodiment, the above-mentioned diamond sintered body preferably further includes a bonding phase, and The above combination contains: At least one selected from the group consisting of the following elemental metals, alloys, and intermetallic compounds, wherein the elemental metals, alloys, and intermetallic compounds include elements selected from Group 4, Group 5, and Group 6 of the periodic table , at least one metal element in the group consisting of iron, aluminum, silicon, cobalt and nickel (hereinafter, also referred to as "group A"); or At least one selected from the group consisting of the following compounds and solid solutions from the above compounds, the above compounds are selected from the group 4 elements, group 5 elements, and group 6 elements of the periodic table, iron, aluminum, silicon , at least one metal element from the group consisting of cobalt and nickel (group A), and at least one metal element selected from the group consisting of nitrogen, carbon, boron and oxygen (hereinafter, also referred to as "group B") Made of non-metallic elements. In other words, the above-mentioned bonding phase can be set to any one of the following forms (a) to (f).

(a) The above-mentioned bonded phase is composed of at least one selected from the group consisting of the following elemental metals, alloys and intermetallic compounds, and the above-mentioned elemental metals, alloys and intermetallic compounds include at least one metal selected from the group A. element.

(b) The bonded phase contains at least one metal element selected from the group consisting of the following elemental metals, alloys and intermetallic compounds, wherein the elemental metals, alloys and intermetallic compounds contain at least one metal element selected from the group A.

(c) The above-mentioned combined phase is composed of at least one selected from the group consisting of the following compounds and solid solutions derived from the above-mentioned compounds, wherein the above-mentioned compound is selected from the group A. It consists of at least one non-metal element in B.

(d) The above-mentioned combined phase contains at least one selected from the group consisting of the following compounds and solid solutions derived from the above-mentioned compounds. of at least one non-metallic element.

(e) The above-mentioned bonded phase is at least one selected from the group consisting of the following elemental metals, alloys, and intermetallic compounds, and at least one selected from the group consisting of the following compounds and solid solutions derived from the above-mentioned compounds. The above-mentioned elemental metals, alloys and intermetallic compounds contain at least one metal element selected from the group A, and the above-mentioned compound is composed of at least one metal element selected from the group A and at least one selected from the group B. Made of non-metallic elements.

(f) The aforementioned combined phase contains at least one selected from the group consisting of the following elemental metals, alloys and intermetallic compounds, and at least one selected from the group consisting of the following compounds and solid solutions derived from the aforementioned compounds , the above-mentioned elemental metals, alloys and intermetallic compounds comprise at least one metal element selected from group A, and the above-mentioned compound is selected from at least one metal element selected from group A and at least one kind of non-metal selected from group B composed of elements.

Group 4 elements of the periodic table include, for example, titanium (Ti), zirconium (Zr), and hafnium (Hf). Group 5 elements include, for example, vanadium (V), niobium (Nb), and tantalum (Ta). Group 6 elements include, for example, chromium (Cr), molybdenum (Mo), and tungsten (W).

In one aspect of the present embodiment, the bonding phase preferably contains at least one selected from the group consisting of cobalt, titanium, iron, tungsten and boron, and more preferably contains cobalt.

The composition of the bonding phase contained in the diamond sintered body can be specified by the EDX attached to the above-mentioned SEM.

(content rate of combined phase) The content of the binder phase is preferably 1% by volume or more and 20% by volume or less, more preferably 10% by volume or more and 20% by volume or less, relative to the above-mentioned diamond sintered body. The content rate (volume %) of the binder phase can be confirmed by performing microstructure observation, elemental analysis, etc. on the diamond sintered body using EDX attached to the above-mentioned SEM.

≪Tools≫ Since the diamond sintered body of the present embodiment is excellent in crack propagation resistance, it is suitably used for cutting tools, wear-resistant tools, grinding tools, tools for friction stir welding, and the like. That is, the tool of the present embodiment includes the above-mentioned diamond sintered body. The above-mentioned tool has excellent damage resistance and excellent impact resistance when machining various materials. When the above-mentioned tool is a cutting tool, the above-mentioned cutting tool is particularly suitable for milling and turning of aluminum alloys (eg, ADC12, AC4B) and the like.

The above-mentioned tool may be composed of a diamond sintered body as a whole, or may be composed of only a part (for example, a tip portion in the case of a cutting tool) of a diamond sintered body.

Examples of cutting tools include drills, end mills, replaceable nose inserts for drills, replaceable nose inserts for end mills, replaceable nose inserts for milling, replaceable nose inserts for turning, Metal saws, gear cutting tools, reamers, screw taps, cutting tools, etc.

As a wear-resistant tool, a die, a scorer, a scorer wheel, a dresser, etc. are mentioned.

As a grinding tool, a grinding stone etc. are mentioned.

≪Manufacturing method of diamond sintered body≫ Manufacturing method of diamond sintered body of this embodiment Has the following steps: Prepare the raw powder of diamond particles and the raw powder of the bonding phase; Mixing the raw material powder of the above-mentioned diamond particles and the above-mentioned raw material powder of the combined phase to obtain a mixed powder; Heating the mixed powder at a holding pressure of not less than 4 GPa but not more than 7 GPa and a holding temperature of not less than 30°C but not more than 600°C for a holding time of not less than 50 minutes but not more than 190 minutes to generate dislocations in the diamond particles; and The mixed powder is sintered at a sintering pressure of 4 GPa or more and 8 GPa or less and a sintering temperature of 1400° C. or more and 1900° C. or less for a sintering time of 1 minute or more and 60 minutes or less.

<Steps for preparing raw powder of diamond particles and raw powder of bonding phase> In this step, raw material powder of diamond particles (hereinafter, also referred to as "diamond powder") and raw material powder of bonded phase (hereinafter, also referred to as "bonded phase raw material powder") are prepared. The diamond powder is not particularly limited, and known diamond particles can be used as the raw material powder.

The average particle size of the diamond powder is not particularly limited, but can be, for example, 0.1 μm or more and 50 μm or less.

The binder phase raw material powder is not particularly limited, as long as it is a powder containing elements constituting the binder phase. As a binder phase raw material powder, cobalt powder, titanium powder, etc. are mentioned, for example. Regarding the binder phase raw material powder, one type of powder may be used alone, or a plurality of types of powder may be used in combination according to the composition of the target binder phase.

<Procedure for obtaining mixed powder> In this step, the raw material powder of the diamond particles (diamond powder) is mixed with the raw material powder of the bonded phase (the raw material powder of the bonded phase) to obtain a mixed powder. At this time, the above-mentioned diamond powder and the above-mentioned bonded phase raw material powder can also be mixed at an arbitrary mixing ratio so that the content of diamond particles in the diamond sintered body falls within the above-mentioned range.

The method of mixing the two powders is not particularly limited, and may be a mixing method using an attritor or a mixing method using a ball mill. The mixing method may be wet or dry.

<Procedure for dislocation of diamond particles> In this step, the mixed powder is heated at a holding pressure of 4 GPa or more and 7 GPa or less and a holding temperature of 30°C or more and 600°C or less, and the above-mentioned mixed powder is heated for a holding time of 50 minutes or more and 190 minutes or less, so that the diamond particles are generated. wrong. By pressurizing the diamond powder at a low temperature where the diamond does not melt and re-precipitate, the crystal structure of the diamond changes and dislocations are generated.

In the present embodiment, the route from the state of normal temperature (23±5° C.) and atmospheric pressure to the state of the above-mentioned holding pressure and holding temperature is not particularly limited.

The high-pressure and high-temperature generator used in the method for producing a diamond sintered body of the present embodiment is not particularly limited as long as it can obtain the desired pressure and temperature conditions. From the viewpoint of improving productivity and workability, the high-pressure and high-temperature generator is preferably a belt-type high-pressure and high-temperature generator. In addition, the container in which the mixed powder is accommodated is not particularly limited as long as it is a material resistant to high pressure and high temperature, and for example, tantalum (Ta), niobium (Nb), etc. are suitably used.

In order to prevent impurities from being mixed into the diamond sintered body, for example, the above mixed powder is first put into a bag made of high melting point metals such as Ta and Nb, heated and sealed under vacuum, so as to remove adsorbed gas and air from the mixed powder . After that, it is preferable to perform the above-mentioned step of dislocating the diamond particles and the following step of sintering the mixed powder. In one aspect of the present embodiment, it is preferable to perform the following step after the above-mentioned step of dislocating the diamond particles, that is, to maintain this state and then sinter the mixed powder without sintering the mixed powder from the above-mentioned high melting point. Take it out of a metal pouch.

The above-mentioned holding pressure is preferably 4 GPa or more and 7 GPa or less, more preferably 4.5 GPa or more and 6 GPa or less.

The above-mentioned holding temperature is preferably 30°C or higher and 600°C or lower, more preferably 50°C or higher and 500°C or lower.

The above-mentioned holding time is preferably 50 minutes or more and 190 minutes or less, and more preferably 60 minutes or more and 180 minutes or less.

<The step of sintering the mixed powder> In this step, the mixed powder is sintered at a sintering pressure of 4 GPa to 8 GPa and a sintering temperature of 1400°C to 1700°C and a sintering time of 1 minute to 60 minutes. Thereby, the diamond sintered body of the present invention is obtained.

The sintering pressure is preferably 4 GPa or more and 8 GPa or less, more preferably 4.5 GPa or more and 7 GPa or less.

The sintering temperature is preferably 1400°C or higher and 1700°C or lower, more preferably 1450°C or higher and 1550°C or lower.

The sintering time is preferably 1 minute or more and 60 minutes or less, and more preferably 5 minutes or more and 20 minutes or less. [Example]

The present embodiment will be described in more detail by way of examples. However, the present embodiment is not limited to these Examples.

≪Production of diamond sintered body≫ <Steps for preparing raw powder of diamond particles and raw powder of bonding phase> The powders having the average particle diameters or compositions shown in Tables 1-1 and 1-2 were prepared as raw material powders.

[Table 1-1] sample Raw powder of diamond particles Raw material powder for combined phase Average particle size (μm) Composition (mass ratio) 1 0.5 Co, Ti (75:25) 2 5.0 Co, Ti (75:25) 3 0.5 Co, Ti (75:25) 4 0.5 Co, Ti (75:25) 5 0.5 Co, Ti (75:25) 6 0.5 Co, Ti (75:25) 7 0.5 Co, Ti (75:25) 8 0.5 Co, Ti (75:25) 9 0.5 Co, Ti (75:25) 10 0.5 Co, Ti (75:25) 11 0.5 Co, Ti (75:25) 12 0.5 Co(100) 13 0.5 Co, Fe (99:1) 14 0.5 Co, B (99:1) 15 0.2 Co, Ti (75:25) 16 0.5 Co, Ti (75:25) 17 5.0 Co, Ti (75:25) 18 30.0 Co, Ti (75:25) 19 45.0 Co, Ti (75:25) 20 55.0 Co, Ti (75:25)

[Table 1-2] sample Raw powder of diamond particles Raw material powder for combined phase Average particle size (μm) Composition (mass ratio) twenty one 30.0 Co, W (95:5) twenty two 40.0 Co, W (95:5) twenty three 30.0 Co, W (95:5) twenty four 30.0 Co, W (95:5) 25 30.0 Co, W (95:5) 26 30.0 Co, W (95:5) 27 30.0 Co, W (95:5) 28 30.0 Co, W (95:5) 29 30.0 Co, W (95:5) 30 30.0 Co, W (95:5) 31 30.0 Co, W (95:5) 32 30.0 Co(100)

<Procedure for obtaining mixed powder> In such a way that the finally obtained diamond sintered body has the composition described in Table 3-1 or Table 3-2, each of the prepared raw material powders was added at various mixing ratios, and mixed in a dry manner using a ball mill to obtain Mix powder. Here, as described below, the mixed powder is sintered in a state of being in contact with a disc made of WC-6%Co cemented carbide. Therefore, when sintering is performed, cobalt and tungsten are leached from the disk into the diamond sintered body, and it is thought that the cobalt content and the tungsten content in the diamond sintered body increase. The mixing ratio of each raw material powder is determined in consideration of the increase in the cobalt content and the increase in the tungsten content in advance.

<Procedure for dislocation of diamond particles> Then, the mixed powder was put into a bag made of Ta in a state of being in contact with a disc made of WC-6%Co cemented carbide, heated under vacuum, and sealed. Then, using a high-pressure high-temperature generator, the above-mentioned mixed powder was heat-treated at the holding pressure, holding temperature and holding time shown in Table 2-1 or Table 2-2.

<The step of sintering the mixed powder> Following the above step of generating dislocations in the diamond particles, the mixed powder was sintered at the sintering pressure, sintering temperature and sintering time shown in Table 2-1 or Table 2-2. Through the above steps, diamond sintered bodies of samples 1 to 32 were obtained.

[table 2-1] sample Steps to generate dislocations Sintering steps Holding pressure (GPa) Holding temperature (℃) Hold time (min) Sintering pressure (GPa) Sintering temperature (℃) Sintering time (min) 1 5 100 200 7 1500 15 2 5 100 220 7 1500 15 3 5 100 180 7 1500 15 4 5 100 160 7 1500 15 5 5 100 140 7 1500 15 6 5 100 120 7 1500 15 7 5 100 100 7 1500 15 8 5 100 80 7 1500 15 9 5 100 60 7 1500 15 10 5 100 120 7 1500 15 11 5 100 120 7 1500 15 12 5 100 120 7 1500 15 13 5 100 120 7 1500 15 14 5 100 120 7 1500 15 15 5 100 120 7 1500 15 16 5 100 120 7 1500 15 17 5 100 120 7 1500 15 18 5 100 120 7 1500 15 19 5 100 120 7 1500 15 20 5 100 120 7 1500 15

[Table 2-2] sample Steps to generate dislocations Sintering steps Holding pressure (GPa) Holding temperature (℃) Hold time (min) Sintering pressure (GPa) Sintering temperature (℃) Sintering time (min) twenty one 5 100 200 7 1500 15 twenty two 5 100 210 7 1500 15 twenty three 5 100 180 7 1500 15 twenty four 5 100 160 7 1500 15 25 5 100 140 7 1500 15 26 5 100 120 7 1500 15 27 5 100 100 7 1500 15 28 5 100 80 7 1500 15 29 5 100 60 7 1500 15 30 5 100 120 7 1500 15 31 5 100 120 7 1500 15 32 5 100 120 7 1500 15

≪Characteristic evaluation of diamond sintered body≫ <Composition of diamond sintered body> The content ratio (volume ratio) of the diamond particles and the bonded phase in the diamond sintered body was measured. The specific measurement method is the same as the method described in the above-mentioned [Details of Embodiments of the Present Invention], so the description will not be repeated. It was confirmed that the content of diamond particles in the diamond sintered body in each sample is as shown in Table 3-1 and Table 3-2 (refer to the column of "content ratio").

<Average particle size of diamond particles> The average particle size of the diamond particles in the diamond sintered body was measured. The specific measurement method is the same as the method described in the above-mentioned [Details of Embodiments of the Present Invention], so the description will not be repeated. The results are shown in Table 3-1 and Table 3-2 (refer to the column of "average particle size").

＜Composition of combined phase＞ The composition of the bond phase in the diamond sintered body was specified by SEM-EDX. The specific measurement method is the same as the method described in the above-mentioned [Details of Embodiments of the Present Invention], so the description will not be repeated. The results are shown in Table 3-1 and Table 3-2 (refer to the column of "composition of binding phase").

<Dislocation Density of Diamond Particles> The dislocation density of the diamond particles in the diamond sintered body was determined. The specific measurement method is the same as the method described in the above-mentioned [Details of Embodiments of the Present Invention], so the description will not be repeated. The results are shown in Table 3-1 and Table 3-2 (refer to the column of "dislocation density").

≪Evaluation of tools with diamond sintered body≫ <Cutting test 1: Milling test> Cutting tools (cutters: RF4080R, inserts: SNEW1204ADFR and The cutting edge part of the blade in the blade replacement type cutter was provided with the above-mentioned diamond sintered body tool), and a milling test was carried out. The cutting conditions of the milling test are as follows. In the above-mentioned milling processing test, the larger the cutting volume (cm ³ ), the more it can be evaluated as a cutting tool having excellent damage resistance and impact resistance. In addition, in this case, the diamond sintered body used for the cutting tool can be evaluated to be excellent in crack propagation resistance. The results are shown in Table 3-1. In the cutting test 1, the samples 3 to 10 and the samples 12 to 14 correspond to the examples. Sample 1, Sample 2, and Sample 11 correspond to comparative examples.

(Cutting conditions for milling test) Work material: ADC12 (60 mm×290 mm×60 mm) Cutting speed: 3000 m/min Feed rate: 0.2 mm/t Notch: 0.4 mm Coolant: wet Evaluation method: Yes The 290 mm×60 mm surface of the workpiece is milled, and the cutting volume (cm ³ ) until the average wear width of the flank surface of the cutting tool reaches 250 μm is determined.

<Cutting test 2: Turning test> The diamond sintered bodies of samples 15 to 20 obtained in the above-mentioned manner were used to manufacture cutting tools (the holder was CSRP R3225-N12, the insert was SPGN120308, and the cutting edge of the insert had the above-mentioned diamond sintered body), and the cutting tools were carried out. Turning test. The cutting conditions of the turning test are as follows. In the above-mentioned turning work test, the longer the cutting distance (km) is, the more it can be evaluated as a cutting tool having excellent fracture resistance and wear resistance. In addition, in this case, the diamond sintered body used for the cutting tool can be evaluated to be excellent in crack propagation resistance. The results are shown in Table 3-1. In the cutting test 2, samples 15 to 19 correspond to the examples. Sample 20 corresponds to the comparative example.

(Cutting conditions for turning test) Work material: Ti-6Al-4V (ϕ120 mm×280 mm) Cutting speed: 270 m/min Feed: 0.12 mm/rev Cutout: 0.35 mm Coolant: wet Evaluation method: Turn the outer diameter of the workpiece, and measure the cutting distance (km) until the average wear width of the flank surface of the cutting tool reaches 200 μm.

[Table 3-1] sample diamond sintered body Performance evaluation diamond particles The composition of the combined phase (mass ratio) Dislocation density (×10 ¹⁶ m ^-2 ) Evaluation method Cutting volume (cm ³ ) or cutting distance (km) Average particle size (μm) Content rate (vol%) 1 0.5 90.0 Co, Ti, W (84:14:2) 1.1 Cutting test 1 initial defect 2 5.0 90.0 Co, Ti, W (84:14:2) 1.15 initial defect 3 0.5 90.0 Co, Ti, W (83:15:2) 1.3 3800 4 0.5 90.0 Co, Ti, W (83:15:2) 1.4 4200 5 0.5 90.0 Co, Ti, W (83:15:2) 1.6 5800 6 0.5 90.0 Co, Ti, W (83:15:2) 6.0 7000 7 0.5 90.0 Co, Ti, W (83:15:2) 9.9 6000 8 0.5 90.0 Co, Ti, W (82:16:2) 10.3 4400 9 0.5 90.0 Co, Ti, W (80:18:2) 13.1 3900 10 0.5 81.0 Co, Ti, W (82:16:2) 6.0 3800 11 0.5 79.0 Co, Ti, W (82:16:2) 6.0 initial defect 12 0.5 90.0 Co.W(98:2) 6.0 4000 13 0.5 90.0 Co, Fe, W (97:1:2) 6.0 7100 14 0.5 90.0 Co, B, W (97:1:2) 6.0 7000 15 0.2 90.0 Co, Ti, W (83:15:2) 6.0 Cutting test 2 3.6 16 0.5 90.0 Co, Ti, W (83:15:2) 6.0 4.1 17 5.0 90.0 Co, Ti, W (83:15:2) 6.0 4.3 18 30.0 90.0 Co, Ti, W (84:14:2) 6.0 4.7 19 45.0 90.0 Co, Ti, W (84:14:2) 6.0 5.1 20 55.0 90.0 Co, Ti, W (84:14:2) 6.0 initial defect

<Results> According to the results of the cutting test 1, the cutting tools of Samples 3 to 10 and Samples 12 to 14 (cutting tools of Examples) obtained good results that the cutting volume was 3800 cm ³ or more. On the other hand, the cutting tools of Sample 1, Sample 2, and Sample 11 (the cutting tools of the comparative example) were chipped at the initial stage of cutting, and the cutting volume could not be obtained. From the above results, it can be seen that the cutting tools of Examples are more excellent in damage resistance and impact resistance than the cutting tools of Comparative Examples. Moreover, it turns out that the diamond sintered compact of an Example is more excellent in crack growth resistance than the diamond sintered compact of a comparative example.

According to the results of the cutting test 2, the cutting tools of samples 15 to 19 (the cutting tools of the examples) obtained good results that the cutting distance was 3.6 km or more. On the other hand, the cutting tool of the sample 20 (the cutting tool of the comparative example) was chipped in the initial stage of the cutting process, and the cutting distance could not be obtained. From the above results, it can be seen that the cutting tools of Examples are more excellent in breakage resistance than the cutting tools of Comparative Examples. Moreover, it turns out that the diamond sintered compact of an Example is more excellent in crack growth resistance than the diamond sintered compact of a comparative example.

<Cutting Test 3: Milling Test> Using the diamond sintered bodies of Samples 21 to 32 obtained in the above-described manner, cutting tools (the cutter: RF4080R, the blade: SNEW1204ADFR, and the blade of the blade replacement type cutter) were used. The tip portion was provided with the tool of the above-mentioned diamond sintered body), and a milling test was carried out. The cutting conditions of the milling test are as follows. In the above-mentioned milling processing test, the larger the cutting volume (cm ³ ), the more it can be evaluated as a cutting tool having excellent damage resistance and impact resistance. In addition, in this case, the diamond sintered body used for the cutting tool can be evaluated to be excellent in crack propagation resistance. The results are shown in Table 3-2. In the cutting test 3, the samples 23 to 30 and the sample 32 correspond to the examples. Sample 21, Sample 22, and Sample 31 correspond to comparative examples.

(Cutting conditions for milling test) Work material: AC4B (60 mm x 290 mm x 60 mm) Cutting speed: 3300 m/min Feed rate: 0.1 mm/t Notch: 0.3 mm Coolant: wet Evaluation method: Yes The 290 mm×60 mm surface of the workpiece is milled, and the cutting volume (cm ³ ) until the average wear width of the flank surface of the cutting tool reaches 250 μm is determined.

[Table 3-2] sample diamond sintered body Performance evaluation diamond particles The composition of the combined phase (mass ratio) Dislocation density (×10 ¹⁶ m ^-2 ) Evaluation method Cutting volume (cm ³ ) Average particle size (μm) Content rate (vol%) twenty one 30.0 95.0 Co.W(93:7) 1.1 Cutting test 3 initial defect twenty two 40.0 95.0 Co.W(93:7) 1.06 initial defect twenty three 30.0 95.0 Co.W(93:7) 1.3 4700 twenty four 30.0 95.0 Co.W(93:7) 1.4 5300 25 30.0 95.0 Co.W(93:7) 1.7 6900 26 30.0 95.0 Co.W(93:7) 4.9 8000 27 30.0 95.0 Co.W(93:7) 9.8 7000 28 30.0 95.0 Co.W(93:7) 10.1 5400 29 30.0 95.0 Co.W(94:6) 13.3 5000 30 30.0 98.0 Co, W (95:5) 4.9 4800 31 30.0 99.2 Co, W (95:5) 4.9 initial defect 32 30.0 95.0 Co.W(98:2) 4.9 5000

<Results> According to the results of the cutting test 3, the cutting tools of samples 23 to 30 and sample 32 (the cutting tools of the examples) obtained good results that the cutting volume was 4700 cm ³ or more. On the other hand, the cutting tools of Sample 21, Sample 22, and Sample 31 (the cutting tools of the comparative example) were chipped at the initial stage of cutting, and the cutting volume could not be obtained. From the above results, it can be seen that the cutting tools of Examples are more excellent in damage resistance and impact resistance than the cutting tools of Comparative Examples. Moreover, it turns out that the diamond sintered compact of an Example is more excellent in crack growth resistance than the diamond sintered compact of a comparative example.

The embodiments and examples of the present invention have been described above, but it is contemplated that appropriate combinations or various changes may be made to the configurations of the above-mentioned embodiments and examples.

It should be construed that the embodiments and examples disclosed this time are illustrative in all respects and not restrictive. The scope of the present invention is indicated by the scope of the patent application rather than by the above description, and is intended to cover the meaning equivalent to the scope of the patent application and all changes within the scope.

Claims (5)

A diamond sintered body comprising diamond particles, and the content rate of the above-mentioned diamond particles is 80% by volume to 99% by volume relative to the above-mentioned diamond sintered body, and the average particle diameter of the above-mentioned diamond particles is 0.1 μm or more. 50 μm Hereinafter, the dislocation density of the above-mentioned diamond particles is 1.2×10 ¹⁶ m ^-2 or more and 5.4×10 ¹⁹ m ^-2 or less. The diamond sintered body according to claim 1, wherein the dislocation density of the diamond particles is 1.5×10 ¹⁶ m ^-2 or more and 1.0×10 ¹⁷ m ^-2 or less. The diamond sintered body of claim 1, which further comprises a bonded phase, and The above combination contains: At least one selected from the group consisting of the following elemental metals, alloys, and intermetallic compounds, wherein the elemental metals, alloys, and intermetallic compounds include elements selected from Group 4, Group 5, and Group 6 of the periodic table , at least one metal element from the group consisting of iron, aluminum, silicon, cobalt and nickel; or At least one selected from the group consisting of the following compounds and solid solutions from the above compounds, the above compounds are selected from the group 4 elements, group 5 elements, and group 6 elements of the periodic table, iron, aluminum, silicon , at least one metal element from the group consisting of cobalt and nickel, and at least one non-metal element selected from the group consisting of nitrogen, carbon, boron and oxygen. The diamond sintered body according to claim 3, wherein the above-mentioned bonding phase contains cobalt. A tool provided with the diamond sintered body as claimed in any one of claims 1 to 4.